1. Field of the Invention
The present invention is broadly concerned with an improved method of performing surgery on a joint surrounded by tissue which permits accurate insertion of instruments into a predetermined location in the joint area with a minimum of trauma to the surrounding tissues. More particularly, it is concerned with a method in which a passageway is created in a predetermined location between the joint area and the external surface; the passageway is enlarged; and a cannula is inserted through which instruments are inserted into the joint area.
2. Description of the Prior Art
Arthroscopic examination of the interior surfaces of various joints and therapeutic procedures within the joints have become relatively commonplace methods of diagnosis and treatment in recent years. These techniques remain limited in their application, however, as to both the joints and patients which may qualify as candidates for such procedures. Healthy, young athletes with lax joints present the most suitable candidates. Patients with loss of motion or narrowing of the joint space are considered less than ideal candidates since introduction of instruments into the joint space is difficult.
A number of methods of performing arthroscopic surgery have been proposed in the past. In general, however, these methods are relatively slow, and have caused excessive trauma to the surrounding tissue resulting in postoperative morbidity, and extended immobilization and rehabilitation.
One such prior method, the spinal needle trial technique, typically involves insertion of a spinal needle from the posterior through layers of fat and muscle until it penetrates the joint capsule. Saline solution is injected for distension and, if the needle is correctly positioned into the joint capsule, saline will freely backflow from the needle. If there is no free backflow, the needle is removed and repositioned, further traumatizing the tissue.
Once correctly positioned, the needle is withdrawn, leaving a puncture wound, and an incision made through the skin at the needle insertion point. A sharp trocar in an arthroscope sleeve is then introduced into the incision and blindly directed along the path of the puncture wound anteriorly to enlarge the pathway and penetrate the capsule. With this technique, because of the small size of the wound left by the needle and the tendency of the surrounding tissue to close in, the trocar frequently deviates from the path of the original puncture, creating a second pathway, and penetrating the capsule at a different point. This results in further trauma to the tissue and multiple punctures through the joint capsule. In addition, the trocar and sleeve may be difficult to visualize through the arthroscope. If the deviation is substantial, it may be necessary to withdraw the trocar and sleeve and attempt another trial. Next, an arthroscope adapter is installed on the sleeve. The arthroscope may be used to visualize the joint area while the method is repeated to establish an alternative portal through which surgical instruments may be inserted.
An alternate procedure using a Wissinger rod may be used to establish an anterior portal. The rod is inserted through the arthroscope cannula into the joint area, and on through the anterior capsular tissue until it tents the anterior skin. Since the rod is inserted through the arthroscope cannula, the arthroscope itself is occluded and cannot be used for visualization of placement of the rod in the joint area. An incision is made in the skin in the area of the tip of the rod and a cannula is passed over the rod and into the joint area. The Wissinger rod is then withdrawn posteriorly.
The Wissinger technique presents some risks in that on certain joints neurovascular structures could be encountered. Additionally, the Wissinger technique is somewhat limited in its application. It is applicable only to joints such as the shoulder in which the rod can pass through the entire joint. In joints such as the knee where the Wissinger technique is inapplicable, the anterior portal must be triangulated by spinal needle trial. The cannula through which the rod is to be inserted must be carefully positioned because its angle of entry predetermines the exit path of the rod. A small variance in the angle of entry necessarily results in a substantial deflection of the exit point. Improper orientation of the rod may result in injury to underlying neurovascular structures.
Where additional portals are required for examination or therapeutic purposes, they must be developed by the spinal trial technique because placement of the rod cannot deviate from the angle predetermined by the angle of placement of the arthroscope.